An improved glycerol biosensor with an Au-FeS-NAD-glycerol-dehydrogenase anode

Abstract

An improved glycerol biosensor was developed via direct attachment of NAD-glycerol dehydrogenase coenzyme-apoenzyme complex onto supporting gold electrodes, using novel inorganic iron (II) sulfide (FeS)-based single molecular wires. Sensing performance factors, i.e., sensitivity, a detection limit and response time of the FeS and conventional pyrroloquinoline quinone (PQQ)-based biosensor were evaluated by dynamic constant potential amperometry at 1.3V under non-buffered conditions. For glycerol concentrations ranging from 1 to 25mM, a 77% increase in sensitivity and a 53% decrease in detection limit were observed for the FeS-based biosensor when compared to the conventional PQQ-based counterpart. The electrochemical behavior of the FeS-based glycerol biosensor was analyzed at different concentrations of glycerol, accompanied by an investigation into the effects of applied potential and scan rate on the current response. Effects of enzyme stimulants ((NH)SO and MnCl·4HO) concentrations and buffers/pH (potassium phosphate buffer pH 6-8, Tris buffer pH 8-10) on the current responses generated by the FeS-based glycerol biosensor were also studied. The optimal detection conditions were 0.03M (NH)SO and 0.3µm MnCl·4HO in non-buffered aqueous electrolyte under stirring whereas under non-stirring, Tris buffer at pH 10 with 0.03M (NH)SO and 30µm MnCl·4HO were found to be optimal detection conditions. Interference by glucose, fructose, ethanol, and acetic acid in glycerol detection was studied. The observations indicated a promising enhancement in glycerol detection using the novel FeS-based glycerol sensing electrode compared to the conventional PQQ-based one. These findings support the premise that FeS-based bioanodes are capable of biosensing glycerol successfully and may be applicable for other enzymatic biosensors.

Inorganic iron-sulfur clusters enhance electron transport when used for wiring the NAD-glucose dehydrogenase based redox system

“…1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-Hydroxysuccinimide (NHS) were purchased from Thermo Fisher Scientific (www.thermofisher.com/us). Fe-S were suspended in ≥99.5% ethanol, and cystamine dihydro chloride was dissolved in pure water; ß-NAD + , GDH, and glutaraldehyde solutions were prepared in a 0.1 M phosphate buffer (pH = 7); PQQ and 3-aminophenylboronic acid solutions were prepared using a 0.1 M HEPES buffer (pH 7.2) in the presence of 5 mM EDC and 2.5 mM NHS [21]. Glucose solutions of different concentrations were prepared in 0.1 M Tris-HCl buffer (pH 8) and stored at 4 °C for 36 ± 1 h to allow mutarotation.…”

“…This work was inspired due to the electron mediating role of iron-sulfur clusters in the biological electron transport chain(s) [16] and the reported performance of iron-sulfur protein derivatives for bioelectrochemical applications [17–20]. The FeS-based electrode assembled during our preliminary work displayed promising electrical charge transport properties, likely, as a result of reduced internal resistance of the enzymatic electrode caused by the shorter FeS single-molecular-wires; and the ability of FeS to be a single-molecular anchor as well as an electron shuttling agent between nicotinamide adenine dinucleotide (NAD + ) coenzyme and the solid electrode support [15, 21]. Although the ability of FeS to anchor and enhance electron transport in the NAD + -GlDH model system was elucidated in our previous work, there is still a gap in knowledge with regard to the utility and performance of other inorganic iron-sulfur compounds for anchoring biomedically relevant redox enzymes such as glucose dehydrogenase.…”

Synthesis of Boron-Doped Non-Flammable Anhydrous Electrolytes for Flexible Quasi-Solid-State Supercapacitor Applications

“…Glycerol, which can be created from vegetable oil, animal fat, or crude oil and widely employed in bio-applications such as additives in drugs and heart disease drugs is one of the most promising options for optimizing the temperature range in electrochemical systems. − Furthermore, in a wide range of industrial processes, glycerol is produced abundantly as a byproduct, which demonstrates the economic feasibility of the material . Many studies have reported that incorporation of glycerol into hydrogel can improve the performance of the electrolyte because of its unique ability to promote ionic conductivity .…”